Quantification and characterization of Ti-, Ce- and Ag5 nanoparticles in global surface waters and precipitation

Nanoparticle (NP) emissions to the environment are increasing as a result of anthropogenic activities, prompting concerns for ecosystems and human health. In order to evaluate the risk of NPs, it is necessary to know their concentrations in various environmental compartments on regional and global scales; however, these data have remained largely elusive due to the analytical difficulties of measuring NPs in complex natural matrices. Here, we measure NP concentrations and sizes for Ti-, Ce-, and Ag-containing NPs in numerous global surface waters and precipitation samples, and we provide insights into their compositions and origins (natural or anthropogenic). The results link NP occurrences and distributions to particle type, origin, and sampling location. Based on measurements from 46 sites across 13 countries, total Ti- and Ce-NP concentrations (regardless of origin) were often found to be within 104 to 107 NP mL–1, whereas Ag NPs exhibited sporadic occurrences with low concentrations generally up to 105 NP mL–1. This generally corresponded to mass concentrations of <1 ng L–1 for Ag-NPs, <100 ng L–1 for Ce-NPs, and <10 μg L–1 for Ti-NPs, given that measured sizes were often below 15 nm for Ce- and Ag-NPs and above 30 nm for Ti-NPs. In view of current toxicological data, the observed NP levels do not yet appear to exceed toxicity thresholds for the environment or human health; however, NPs of likely anthropogenic origins appear to be already substantial in certain areas, such as urban centers. This work lays the foundation for broader experimental NP surveys, which will be critical for reliable NP risk assessments and the regulation of nano-enabled products

Release of TiO2 nanoparticles from painted surfaces in cold climates : characterization using a high sensitivity single-particle ICP-MS

Paints and coatings represent one of the major applications of TiO2 nanoparticles (NPs). While it has been previously shown that NPs are released from painted surfaces, there is still a lack of experimental data on their release rates under natural conditions and on the size distributions of the NPs following release. This study quantifies TiO2 NP release from painted surfaces under natural weathering conditions and identifies the main seasonal factors that contribute to increased NP release. First, an analytical methodology using a highly sensitive single particle inductively coupled plasma mass spectrometer (SP-ICP-MS) was developed that improved the size detection limit (SDL) of the technique down to <20 nm for TiO2 NPs. Precipitation (rain, snow) was collected after it came into contact with painted panels that were exposed to natural weathering. NPs that were released from the paint, as well as those pre-existing in the precipitation were thoroughly characterized with respect to their size distributions, particle number concentrations and total metal content. During the 10 week winter exposure, 3 × 1011 NP per m2 were released, corresponding to <0.001% of the TiO2 NP load on the panels, with most of the NPs found in the 20–60 nm range. Significantly fewer NPs were released during the summer than the winter, in spite of the fact that there was more precipitation in the summer. Controlled lab weathering experiments revealed that NP release was significantly enhanced for wet surfaces, particularly, when the samples underwent freeze–thaw cycles. The results also indicated that NP release and loss (i.e. through agglomeration, sedimentation or sorption, etc.) are dynamic processes that are a function of the physical and chemical properties of the external medium. Although NP release is a primary determinant in environmental risk, subsequent NP behavior leading to losses or re-suspension can be equally critical

Transformations of Silver Nanoparticles in Wastewater Effluents: Links in Ag Bioavailability

Wastewater effluents represent one of the main routes through which silver nanoparticles (Ag NPs) can reach natural aquatic environments, where they may interact with a range of organisms. However, in wastewaters, Ag NPs may undergo different chemical and physical transformations, which may alter NP toxicity towards aquatic organisms. The main objectives of this study are to characterize the dissolution and speciation of a Ag NP in a wastewater effluent and to assess its interactions with a model organism, Chlamydomonas reinhardtii (green alga), in the same medium. Experiments were conducted to distinguish the effect(s) of the wastewater matrix on the dissolution of Ag NPs and to determine whether the transformed NPs or the dissolved Ag species would be more bioavailable to C. reinhardtii. It was shown that in the wastewater effluent, Ag bioavailability was significantly reduced with respect to experiments using similar Ag concentrations in simple media. The substantial reduction in Ag bioavailability in wastewaters could be explained by the presence of high concentrations of organic/inorganic ligands, which complexed the Ag and the presence of substantial competing ions.[...

Measurement of CeO2 Nanoparticles in Natural Waters Using a High Sensitivity, Single Particle ICP-MS

As the production and use of cerium oxide nanoparticles (CeO2 NPs) increases, so does the concern of the scientific community over their release into the environment. Single particle inductively coupled plasma mass spectrometry is emerging as one of the best techniques for NP detection and quantification; however, it is often limited by high size detection limits (SDL). To that end, a high sensitivity sector field ICP-MS (SF-ICP-MS) with microsecond dwell times (50 &micro;s) was used to lower the SDL of CeO2 NPs to below 4.0 nm. Ag and Au NPs were also analyzed for reference. SF-ICP-MS was then used to detect CeO2 NPs in a Montreal rainwater at a concentration of (2.2 &plusmn; 0.1) &times; 108 L&minus;1 with a mean diameter of 10.8 &plusmn; 0.2 nm; and in a St. Lawrence River water at a concentration of ((1.6 &plusmn; 0.3) &times; 109 L&minus;1) with a higher mean diameter (21.9 &plusmn; 0.8 nm). SF-ICP-MS and single particle time of flight ICP-MS on Ce and La indicated that 36% of the Ce-containing NPs detected in Montreal rainwater were engineered Ce NPs